History of the West Nile Virus

In 1937, West Nile virus was first isolated from a feverish woman in the West Nile district of Uganda in Central Africa. The virus became recognized as a cause of severe human Meningoencephalitis (inflammation of the spinal cord and brain) in elderly patients during an outbreak in Israel in 1957. Eastern Equine Encephalitis (affecting horses) was first noted in Egypt and France in the early 1960's.

In 1999, West Nile virus first appeared in North America, with encephalitis being reported in humans and in horses. This is an important milestone in the history of this virus. For current reports of West Nile Virus infections by the Center for Disease Control, visit 2012 West Nile Virus Data and Maps.

West Nile Virus Hotline: (800) 232-4636 or TTY (888) 232-6348

What is West Nile Virus?

A virus that is transported by migrating birds and transmitted by mosquitoes that can cause Encephalitis (inflammation of the brain) or Meningitis (Inflammation of the lining of the brain and spinal cord).

West Nile virus detected in Florida

On July 6, 2001, West Nile was confirmed by the Department of Health in a crow from Jefferson County, marking the first time West Nile had been detected in the state. Human cases have been confirmed as well.

On November 9, 2001, a chicken and a dead crow tested positive for West Nile in Brevard County, Florida.

How does the virus get into humans?

Mosquitoes become infected when they feed on infected birds. Infected female mosquitoes can then transmit West Nile virus to humans and animals while biting to take blood. The virus is located in the mosquito's salivary glands. During blood feeding, the virus may be injected into the animal or human, where it may multiply, possibly causing illness.

Neither you nor your child can get West Nile virus from a person who has the disease. West Nile is not spread by person-to-person contact such as touching, kissing, or caring for someone who is infected.


Most people who become infected with West Nile either have no symptoms or experience mild illness such as fever, headache and body aches before fully recovering. Some people develop a mild rash or swollen lymph glands. In some individuals, particularly the elderly, West Nile can cause serious disease that affects brain tissue. In humans with a weak immune system and the elderly, West Nile can cause permanent neurological damage and can be fatal. Healthy adults and children usually have mild reactions.

Symptoms of Encephalitis (inflammation of the brain) include:

  • High fever
  • Severe headache
  • Rash
  • Swollen lymph nodes
  • Gastrointestinal problems
  • Eye Pain
  • Achy muscle
  • Muscle weakness
  • Back pain
  • Stiff neck
  • Confusion
  • Loss of consciousness

Incubation period

From the time you were bitten to the time of noticing symptoms is 3 to 15 days. Vaccine for West Nile: There is no vaccine for humans at this time.

Personal protection

  • Try to stay inside during peak biting times (dawn, dusk, and early evening)
  • Wear long-sleeved shirts and long pants when you go out.
  • Loose clothing.
  • Light colored clothing.
  • Apply insect repellent sparingly to exposed skin. An effective repellent will contain 35% DEET. DEET in high concentrations (greater than 35%) provides no additional protection.
  • Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children.
  • When using repellents always read and follow directions for use as printed on the product

What you can do to help

  • Throw out old tires (you can put out at least 2 per week with the trash).
  • Throw out tin cans, buckets, drums, bottles, or any water holding containers.
  • Fill in or drain any low places (puddles, ruts) in yard.
  • Keep drains, ditches, and culverts clean of weeds and trash, so water will drain properly.
  • Cover trash containers to keep out rainwater, and drill holes in bottom of trash containers so any water can drain out.
  • Repair leaky pipes and outdoor faucets.
  • Empty plastic wading pools at least once a week or store in a position that water will drain.
  • Make sure your backyard pool is maintained properly.
  • Fill in tree rot holes and hollow stumps that hold water with sand or concrete.
  • Change water in bird baths and plant pots or drip trays at least once a week.
  • Keep grass cut short and shrubbery well trimmed around the house, so adult mosquitoes will not hide there.
  • Keep gutters clean and free of debris and leaves.